The bank worked on deals equal to 37% of the total value of equity sales in the region in the first half, compared with 26% for second-placed CIMB Group Holdings Bhd., data compiled by Bloomberg show.

UBS won roles on the biggest-ever share sales in the Philippines, Thailand and Indonesia, including PT Matahari Department Store’s $1.4bn offering in March.

UBS is pushing investment bankers and private bankers to cooperate to generate underwriting work in a region where the number of millionaires is rising faster than in developed economies, said Stuart Mackay, head of equity capital markets for Southeast Asia. The firm was tied with Citigroup as the biggest private bank in the Asia-Pacific region last year, according to the Boston Consulting Group.

'We’ve always worked closely, and the integration is getting even better', Mackay, who moved to Singapore from Hong Kong in 2011, said in an interview. 'It was particularly clear to me that Southeast Asia was going to produce a lot of business for the next couple of years'.